Piercing and forming are common to many industrial fabrication processes. Often, it is necessary to form or emboss a workpiece to a net position. A net position is achieved when, regardless of the placement of the workpiece relative to the tooling, the workpiece is embossed to the same position relative to the base, or some other constant position. Embossing a workpiece to a net position is important when aligning a number of internal support members together which will subsequently have external panels mounted thereon.
For example, often times the workpiece to be embossed is associated with a frame. The frame includes many attached parts. These parts may not always be flush or properly aligned. In the prior art, pads are drawn out from the various parts, and panels are mounted on the pads. However, the prior art provides for drawing the metal out a set distance, i.e. one-half inch. If one-half inch pads are drawn out uniformly from misaligned pieces, the pads will also be misaligned as well as the subsequently attached panels.
Additionally, many devices of the prior art provide for equalization about a workpiece. Equalization describes the process by which a tool is brought up to the workpiece and stopped at contact. Equalization of the tooling about the workpiece prevents unnecessary damage to the workpiece prior to forming. Equalization in the prior art has been accomplished through a variety of mechanisms, including springs and hydraulic cylinders. Two mechanism of equalization are described in U.S. Pat. No. 3,008,032, to Wolfbauer et al, and U.S. Pat. No. 3,396,260 to Waltonen.
Besides providing a device to form a workpiece it is often advantageous to provide a device operable in forming and piecing a workpiece. Such dual function apparatus provide efficient utilization of machinery by eliminating the need for additional equipment. Additionally, such dual function machinery in the prior art is large and cumbersome to use.
For example, U.S. Pat. No. 5,054,305 to Obrecht et al. discloses a multiple function hydraulic apparatus comprising an upper and a lower slide assembly which operate to reciprocally move in an equalized fashion. The device includes four cylinders: the first cylinder equalizes the device about a workpiece; the second cylinder operates to form the workpiece; the third cylinder operates to pierce the workpiece; and the fourth cylinder drives a wedge into a hole to lock half of the forming mechanism against the workpiece. The Obrecht device is extremely bulky and cumbersome due to the numerous cylinders and their varying orientation.
Therefore, there is a need to provide a more compact mechanism capable of forming a workpiece to a net position and piercing the workpiece. The present invention solves these and other problems of the prior art.